lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Thu, 12 Oct 2017 09:16:39 +0200 From: Dmitry Vyukov <dvyukov@...gle.com> To: Andrew Morton <akpm@...ux-foundation.org> Cc: Abbott Liu <liuwenliang@...wei.com>, Russell King - ARM Linux <linux@...linux.org.uk>, Andrey Ryabinin <aryabinin@...tuozzo.com>, afzal.mohd.ma@...il.com, f.fainelli@...il.com, Laura Abbott <labbott@...hat.com>, "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>, Michal Hocko <mhocko@...e.com>, cdall@...aro.org, marc.zyngier@....com, Catalin Marinas <catalin.marinas@....com>, Matthew Wilcox <mawilcox@...rosoft.com>, Thomas Gleixner <tglx@...utronix.de>, Thomas Garnier <thgarnie@...gle.com>, Kees Cook <keescook@...omium.org>, Arnd Bergmann <arnd@...db.de>, Vladimir Murzin <vladimir.murzin@....com>, tixy@...aro.org, Ard Biesheuvel <ard.biesheuvel@...aro.org>, robin.murphy@....com, Ingo Molnar <mingo@...nel.org>, grygorii.strashko@...aro.org, Alexander Potapenko <glider@...gle.com>, opendmb@...il.com, linux-arm-kernel@...ts.infradead.org, LKML <linux-kernel@...r.kernel.org>, kasan-dev <kasan-dev@...glegroups.com>, "linux-mm@...ck.org" <linux-mm@...ck.org>, jiazhenghua@...wei.com, dylix.dailei@...wei.com, zengweilin@...wei.com, heshaoliang@...wei.com Subject: Re: [PATCH 06/11] change memory_is_poisoned_16 for aligned error On Thu, Oct 12, 2017 at 1:23 AM, Andrew Morton <akpm@...ux-foundation.org> wrote: > On Wed, 11 Oct 2017 16:22:22 +0800 Abbott Liu <liuwenliang@...wei.com> wrote: > >> Because arm instruction set don't support access the address which is >> not aligned, so must change memory_is_poisoned_16 for arm. >> >> ... >> >> --- a/mm/kasan/kasan.c >> +++ b/mm/kasan/kasan.c >> @@ -149,6 +149,25 @@ static __always_inline bool memory_is_poisoned_2_4_8(unsigned long addr, >> return memory_is_poisoned_1(addr + size - 1); >> } >> >> +#ifdef CONFIG_ARM >> +static __always_inline bool memory_is_poisoned_16(unsigned long addr) >> +{ >> + u8 *shadow_addr = (u8 *)kasan_mem_to_shadow((void *)addr); >> + >> + if (unlikely(shadow_addr[0] || shadow_addr[1])) return true; > > Coding-style is messed up. Please use scripts/checkpatch.pl. > >> + else { >> + /* >> + * If two shadow bytes covers 16-byte access, we don't >> + * need to do anything more. Otherwise, test the last >> + * shadow byte. >> + */ >> + if (likely(IS_ALIGNED(addr, KASAN_SHADOW_SCALE_SIZE))) >> + return false; >> + return memory_is_poisoned_1(addr + 15); >> + } >> +} >> + >> +#else >> static __always_inline bool memory_is_poisoned_16(unsigned long addr) >> { >> u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr); >> @@ -159,6 +178,7 @@ static __always_inline bool memory_is_poisoned_16(unsigned long addr) >> >> return *shadow_addr; >> } >> +#endif > > - I don't understand why this is necessary. memory_is_poisoned_16() > already handles unaligned addresses? > > - If it's needed on ARM then presumably it will be needed on other > architectures, so CONFIG_ARM is insufficiently general. > > - If the present memory_is_poisoned_16() indeed doesn't work on ARM, > it would be better to generalize/fix it in some fashion rather than > creating a new variant of the function. Yes, I think it will be better to fix the current function rather then have 2 slightly different copies with ifdef's. Will something along these lines work for arm? 16-byte accesses are not too common, so it should not be a performance problem. And probably modern compilers can turn 2 1-byte checks into a 2-byte check where safe (x86). static __always_inline bool memory_is_poisoned_16(unsigned long addr) { u8 *shadow_addr = (u8 *)kasan_mem_to_shadow((void *)addr); if (shadow_addr[0] || shadow_addr[1]) return true; /* Unaligned 16-bytes access maps into 3 shadow bytes. */ if (unlikely(!IS_ALIGNED(addr, KASAN_SHADOW_SCALE_SIZE))) return memory_is_poisoned_1(addr + 15); return false; }
Powered by blists - more mailing lists